Before you run this jailbreak—or any, really—it's probably a good idea to back up all your stuff to iTunes or iCloud and disable passcode locking your device if you have it enabled. From there, everything should be a piece of cake.

You can go grab your Windows, OS X, or Linux executable over at evasi0n.com. There are 25 mirrors for the file, and you'll automatically be routed to the one with the least resistance, so you should be able to pull down that file easily, even in the heat of the moment. Now go enjoy your sweet, sweet jailbreak freedom.